1. Field of the Invention
The present invention relates to a method, system, and program determining whether data has been modified.
2. Description of the Related Art
In a network environment, client systems may maintain a local version of data from a database at a server, where each client may maintain a different subset of the data at the server database. Periodically, the clients may request synchronization of the subset of data at the client local database and corresponding data at the server database. As part of such synchronization, the server may provide a copy of the entire subset of data the client maintains from the server database. This copy may include data that has changed and not changed since the last synchronization. This prior art technique needlessly consumes network resources to transmit data that has not changed and that the client does not need to synchronize.
Another prior art technique is for the server system to scan the entire server database to find any of the subsets of data being synchronized that have changed since the last synchronization, and then send to the client only the data that has changed. This prior art technique requires that the server scan the entire database for data corresponding to the client subset of data that has changed even if some or all of the client subset of data has not changed. This process of scanning the database can consume significant server and database resources if multiple clients are requesting synchronization concurrently. For each requesting client, the server would have to open a connection with the database and scan the entire database for changes to the subset of data being synchronized.
For these reasons, there is a need in the art for improved techniques for detecting changes in data.